There are many applications in the oil and chemical industries where liquid streams are distributed in a vessel or tank for the purpose of achieving a uniform residence time within the vessel or tank. Examples are liquid phase reactors, liquid-liquid or gas-liquid separators and electrostatic precipitators. In these applications, it is desirable to provide liquid distribution uniformly across a horizontal cross-section of the vessel or tank. Uniformly distributing the liquids maximizes the apparent residence time within the vessel. The size vessel required for the service is thereby reduced or the results achieved by a certain vessel are increased.
Inlet streams to separators are typically distributed by perforated-pipe distributors. A perforated-pipe distributor is a pipe having nozzles (typically holes drilled through the pipe) along its length to distribute the inlet flow into the vessel along the length of the pipe. When the separator is a horizontal vessel, a single distributor is often provided parallel to the longitudinal axis of the vessel, near the bottom of the vessel. A plurality of parallel distributor pipes have been provided in order to improve the utilization of the vessel's volume. A plurality of parallel distributor pipes would be expected to distribute the inlet stream over a larger portion of the cross section of the vessel, resulting in greater utilization of the vessel volume, but this has not been the typical result. Distribution of the inlet streams from parallel sets of distributor pipes has typically not been uniform, because of poor distribution to the parallel branches of the distributor. This results in a decrease in the effectiveness of the utilization of the vessel's volume.
When parallel distributor pipes have been provided as branches from a central distribution manifold, slug flows and surging inlet flows tend to move the distributors from an initial level orientation. This results in some branches being higher than others. When the inlet stream is buoyant compared to the liquids surrounding the distributor due to, for example, the inclusion of a vapor in a vapor-liquid feed stream, much more of the inlet flow will go to the higher branches. Once poor distribution begins, it will often become worse over time because branches having of lower flow rates will more quickly become plugged. Providing multiple branches also splits the flow into smaller portions, and decreases the hydraulic pressure drop in each branch. Either smaller diameter pipes must be used for the branches or the velocity of the fluids in the branches will be significantly decreased. Either of these options result in an increased tendency for the branches, and the nozzles, to plug.
It is therefore an object of the present invention to provide an apparatus to distribute flow of a liquid phase into a vessel that provides improved utilization of the vessel's volume. It is another object to provide such an apparatus wherein the apparatus contains two laterals and flow will be distributed effectively in the event that one of the two lateral becomes plugged, and in the event that the apparatus is not in a horizonal plane.